Blog Stats

Contact Me

Laser Cutting

It has been about a year since my last attempt at building a functional touch slider that works with custom Project Diva controllers but its back! It was a combination of seeing a 18×24″ piece of single sided copper clad FR4 in my amazon recommended bar, not wanting to invest $1000 into developing a hobbyweight Combat Robot, and a new copper sensor layout idea that I saw on a datasheet.

I knew from my last “attempt” that a lot had to change. The three main things were to significantly shorted the traces from sensor pad to MPR121, less gap between sensor pads, and to zig-zag the sensors allowing for better contact on multiple pads while also increasing overall width. With these criteria in mind, I went to Inventor and whipped up a few sketches of different patterns and imported to CorelDraw. After filling in the bits that needed filling in, I set the whole file to inverse color and I was ready for the laser cutter. For anyone following along at home, this is the image to use if you want to attempt your own. If you have CorelDraw, I can give you the native file to import instead of using the JPEG below.

For anyone not familiar with making a PCB with a laser cutter, it is done by spraying the entire board with paint, and etching away the negative of your copper layout. After a little cleaning with rubbing alcohol, the whole board is etched in ferric chloride. For anyone following along at home, my laser settings on an Epilog 40W laser were speed 5% and power 10%. My next attempt will probably be 12-15% to remove a little more on those thin traces between the contacts, two were bridged after etching.

With the board etched, the last two steps are to acetone away the remaining paint, and to drill the holes

Not pictured is where I am currently. I drilled the holes and attached the first MPR121 breakout board and it is working fantastic with the first 12 sensor pads. the next step is to wire up the other four and try to get some working code which is always the hardest part for me.

UPDATE 7/29/18:

I got some base code to work off of from Reddit user u/Fatso666 and modified it to work with all four sensors. Did a little cleanup and it’s working! I unplugged the middle four arrows for the time being to plug into the Arduino that is hiding underneath the controller and taped a box behind to hold up the slider but everything registers without issue. I will still be working to revise the code to operate smoother and more efficient. I may try to possibly add code for tracking LEDs up top just like the real cabinet but I don’t want to get ahead of myself just yet.

Also this means I have to build another controller being a 1:1 replica of the input face. DivaPRO? DivaUltimate?

This latest addition to my growing collection of Project Diva: Future Tone controllers is a 1:4 scale version of the full arcade layout. At its heart is a Brook PS3/PS4 fighting board and four Seimitsu PS-14-DN 24mm buttons. Housed inside of a laser cut ABS case provides durability and style. In addition, this iteration features a brand new input method by means a capacitive touch sensor.

The touch pad is manufactured by Brook and has approximately the same dimensions as the Dual Shock 4 touch pad. The USB cable is detachable with a micro-XLR 4 pin connector and tech-flex covering for protection. While this is a finished prototype, the rough ABS edges are still far from perfect and will likely use white acrylic in the final version.

As for now, the controller is not for sale and the design will receive a few more iterations to increase internal space, strength, and ease of assembly. After these updates, the files will likely be uploaded to Instructables along with full assembly instructions. If I do manufacture finished controllers if anyone actually wants one of these tiny (but still fully usable) controllers, estimated price will be around $199 USD.

Laser cutting ABS is possible, however, it is not really safe to breathe and the cuts are not too clean. The following is all based off using an Epilog Helix 40 watt laser with air assist and a fume extractor. Air assist and a fume extractor are essential for ABS.

First, some background on ABS. It’s full name is Acrylonitrile butadiene styrene. It has a relatively low melting point, flexibility, and strength which makes it great for 3D printing, vaccuum forming, injection molding. These same properties make it a pain on the laser as it results in yellow/rough edges and warping which moves the work piece out of focus. The other problem is when melted, ABS outgasses HYDROGEN CYANIDE which is not good to breathe so make sure you have your fume extractor set up and turned on.

To counter this I have found the following tips and tricks to minimize problems.

Test cut a piece of your material to calibrate your settings. On white ABS for vector cuts I use 100% power, 8% speed, and 5000hz frequency.

Use blue tape on both sides, this prevents most of the melting fro. Ruining the edges and the smoke from damaging the color

If your work piece is large enough, use hard drives or other objects to weigh down your sheet to counter warping

Use air assist and if possible, use a nitrogen air assist to prevent flame-ups.

Wash your parts with soap and water after cutting to remove some of the smell

It is a tricky material and will require some fine tuning but this will definitely get you started.